Vented mold and apparatus for making same



Patented Sept. 14, 1937 UNITED STATES PATENT OFFICE VENTED MOLD AND APPARATUS FOR MAKING SAME William H. Millspaugh, Catawba Island, Ohio, assignor to Centrifugal Steel, Inc., Sandusky, Ohio, a corporation of Ohio Application May 23, 1935, Serial No. 22,935

11 Claims.

This invention relates to vented molds and to the method of making same.

Its object is to improve upon molds previously used and to provide a novel method of making them.

Refractory lined molds are used in making certain types of castings centrifugally. Such gases as are entrapped between the casting and the inner surface of the mold or which are liberated in the mold lining itself, must escape outwardly in order to make a perfect casting. To that end it has been necessary heretofore to provide perforated flasks. In making certain castings cooling water is applied to the outside of a the flask. When the latter is perforated this dampens the refractory liner and causes vapor pressure to be developed which results in injury to the casting. This difficulty may be overcome by making a vented mold within a solid flask in 7 1 the manner herein set forth.

I will describe two methods of making vented molds according to my invention.

Referring to the drawing,

Fig. 1 is a sectional elevation of a vented mold 25 in process of construction and of the parts which are used for making it;

Fig. 2 is a perspective view of a plug or pattern and vent forming equipment which is shown in Fig. 1;

30 Fig. 3 is a partial enlarged sectional elevation of some of the parts shown in Fig. 1; 1

Fig. 4 is an inverted sectional plan view of the parts shown in Fig. 3, the section being taken on the line 4--4 of Fig. 3;

35 Fig. 5 is a view similar to Fig. 3 illustrating another construction;

Fig. 6 is a plan view of the parts shown in Fig. 5, the section being taken on line 66 of Fig. 5; and

4.0 Fig. '7 is a sectional elevation of a part of the upper portion of a finished mold made according to this invention and a face plate aflixed to a rotor, a part of which is shown. Like characters of reference designate corre- 45 sponding parts on each side of the figures.

II! designates a hollow cylindrical flask of indeterminate length and with imperforate walls. In forming a refractory liner within this flask, a stop-off II is placed within it in a position 50 which predetermines the length of the finished mold and the flask is placed in a vertical position.

The stop-off is constructed with a central part forming a cylindrical opening I2, and a flat disc .55 I3 placed slightly below the upper edgeof this central part to form an annular shoulder I4. Its outerportion I5 is cylindrical and is adapted to fit the inner surface of the flask III. This is provided with a plurality of grooves I6, parallel with its axis and extends up above the disc I3 5 to form a shoulder I'I. I8 is a facing on the disc I3 between the shoulders I4 and I1 and preferablyoverlapping the former. This facing may be a metal plate or of refractory material as shown, eitherrammed and dried in place or pre- 10 molded. Its object is to protect the stop-off in use from injury from excessive heating. I9 is an annular band of a fusible plastic material such as wax, tar, bituminous matter or a mixture of suitable materials, in the upper, outer part of the shoulder I! which is recessed to receive it, as best shown in Fig. 3.

is a cylindrical ramming plug, the outer diameter of which is that of the inner diameter of the finished mold. This is suspended by ropes or cables 2|, by means of which it may be lowered onto the stop-off I I. 22 is a boss which projects below the plug 20 into the opening I2 of the stop-01f to center the lower end of the plug.

23 are guides affixed to the upper end of the plug 20 which extend outwardly to fit the flask I0 to center the upper end of the plug. 24 is a ring which rests upon or is afiixed to the guides 23. Aflfixed to the ring 24 and depending therefrom is a plurality of rods 25. These are substantially half round in cross-section with their flat'or nearly flat sides lying against the inner surface of the flask. Their lower ends extend below the lower end of the plug 20. This forms what has been referred to as a vent forming equipment.

When the plug is lowered onto the stop-01f, the rods 25 penetrate the plastic ring I9 and will be held thereby against displacement during the first part of the ramming operation which I will 40 now describe.

With the parts in the relative positions in which they are shown in Fig. l, refractory material 30 is dropped into the space between the inside of the flask Ill and the outside of the plug 20, a part of which space is occupied by the rods 25. As this material is supplied it is rammed or tamped down into a nearly solid mass. This operation is continued so that a liner is built up gradually around the plug 20 with the rods 25 embedded in it.

After the liner has been thus formed around the plug, for at least a substantialpart of its length, the plug is raised in the liner but not out of it. Its lower end is then centered in theliner itself.

, guide the lower'end of the plug when it is raised to a still higher position. These steps are continued until the ring 24 is raised above the top of the flask. Refractory material is still supplied and tamped in place until the liner is completed ;to the end of the flask. Then the plug and the rods are hoistedj clear of the lined flask, a stripping plate being provided to hold the top of the 'Thus, a mold mold from lifting. 7

The lined flask is thereafter put in a. drying oven and subjected to heat, applied for the primary purpose of baking the refractory material. The heat, however, has the further effect of melting the plastic ring I 9, and it will runout leaving an annular void in the space it originally occue pied. a

comprising an imperforate flask with a refractory lining is produced with longitudinal vent channelsextending'from end to end. The stop-off 40, shown in Figs. and 6,"difiers from that previously described in that the upper portion of its outer part is provided with grooves 4| shapedto receive the ends of rods 25. These Sgrooves extend down to and communicate with an annular cavity 42. Vent grooves'43 are shown extending from this cavity 42 to the bottom of the stop-off, but with this construction these are not necessary. Axial passages 44 extend inwardly from the annular cavity to the bottom of the stop-off. a V

' Themethod of constructing a mold with this form of stop-off is similar to that already described, except that there is no plastic ring to be melted out. 'The passages 44 are extended in wardly so that any foreign matter which may be dislodged during the operation of the mold, which might fall into the annular cavity 42, will be retained therein by centrifugal force, and will, not

' passinto the passages 44 to clog them or to be discharged through them.

In Fig. '7, a face plate which end ofea rotor 5|, holds the finished mold in place. 7 The upper end of the flask is flanged and held between the faceplate and therotor. A packing or seal 52 is placed between the upper endof the liner 30 and 'a facing similar to that in the stop-. off (Fig. 3). An annular space 53 is formed aroun'd'the outside of the seal. Radial grooves 54 in'the inner surface of the face plate communicate with this annular space and providefor the ,of said liner, and a transverse stop-off constructed to form passages communicating with the passages in the liner.

'2. A mold comprising an imperforate flask, a liner of refractory material therein constructed to form a plurality'of parallel longitudinal venting passages therein adjacent the inner surface of the flask, extending through the ends of said is affixed to the liner, and a' transverse stop-off constructed to.

form passages communicating with-the passages V in the liner and leading inwardly therefrom.

3. A mold comprising an imperforate flask, a liner of refractory material therein constructed to form a plurality of parallel longitudinal venting passages therein adjacent the inner surface of r the flask, extending through the ends of said liner, and atransverse stop-off constructed to form an annular cavity communicating with the passages in the liner and a passage leading inwardly from said. cavity'and out through the end of the stop-off. 7

4.,A mold comprising an imperforate flask, a liner. of refractory materialtherein constructed to form a plurality of parallel longitudinal venting passages therein adjacent the inner surface of the flask, extending through the ends of said liner, and a transverse stop-off constructed to form an annular cavity communicating with the out through the endof the stop-off. I i

5. A device for lining cylindrical flasks comprising a longitudinally movable plug of less diameter than the inner diameter of the flask, an annular ring arranged to flt slidably within the flask carried by one end of the plug and movable therewith-to center'and guidethe plug, and a V plurality of rods parallel with the axis'of the plug aflixed to said ring,

6. A cylindricalfiask and a stop-off therein combined with a longitudinally movable plug of less diameter than the inner diameter of the flask, means for centering one end of the plug in the stop-off, an annular ring arranged to fit within the flask carried by the other end of theplug and to center said end' and movable with the plug, a plurality of rods parallel with the axis W of the plug afiixed to said ring, and means for positioning the ends of the rods in said stop-off. 7. A cylindrical flask and a stop-off therein combined with a longitudinally movable plug of less diameter than the inner diameter of 'the flask, arranged to be seated on the stop-off and to be centered thereby, an annular ring arranged to fit within the flask carried by the other end of the plug and to center said'end and movable with the plug, a plurality of rods parallel with the axis of the plug 'aflixed to said ring and extending beyond the other end of the plug into the stop-off when the-plug is seated thereon.

8. A cylindrical flask, a stop-01f therein and an annular ring of fusible plastic material seated in the stop-Off combined with a longitudinallymov able plug of less diameter than the inner diam .eter of the flask, arranged to be seated on the 9. A cylindrical flask and a stop-off therein" combined with a longitudinally movable plug of less diameter tha n the inner diameter of the flask, arranged to be seatedon the stop-off and to be centered thereby, an annular ring arranged 'to fit within the flask carried by the other end of the plug and to center said end and movable with the plug, a plurality of rods parallel with the axis of the plug affixed to said ring, extending beyond the other end of the plug into the stop-off when the plug is seated thereon, and means for moving the plug and the rods longitudinally.

10. A cylindrical flask, a stop-off therein combined with a longitudinally movable plug of less diameter than the inner diameter of the flask, arranged to be seated on the stop-off and to be centered thereby, an annular ring arranged to fit within theflask carried by the other end of the plug and to'center said end and movable with the plug, an annular ring of fusible plastic material seated in the stop-off, a plurality of rods parallel with the axis of the plug afiixed to said ring carried by the plug, extending into said ring of plastic material when the plug is seated in the stop-off, and means for moving the plug and the rods longitudinally.

11. A mold comprising an imperforate flask, a liner of refractory material therein constructed to form a plurality of parallel longitudinal venting passages therein extending through the ends of said liner, a transverse stop-off at one end of. the liner, and a face plate at the other end of the liner, said stop-off and face plate being constructed to form passages communicating with the passages in the liner.

WILLIAM H. MILLSPAUGH. 

